3.06.2009

Comparing the modern MBT (main battle tank) and that of a tank from the second world war is similar to comparing the Porsche to the Model T. Tank design and doctrine has changed so much since WWII that to many tankers of the period our MBTs would seem quite foreign.

In WWII each army had subdivisions of tanks, usually into Infantry Support (normal tanks like the Sherman and Panzer IV), Tank Destroyers (Stug or M10 series) or Self Propelled Guns (Wespe, Priest). The first and the last groups are still very much alive in today's military but the role of tank destroyer has essentially dropped out. Why you ask?

It is not so much that gun design has changed - in fact it really hasn't changed much in the last hundred years. It is still a rifled barrel (or smoothbore in case of the Leopard and Abrams) that is designed to withstand a controlled explosion and hurl a projectile. They have only gotten bigger. But they are not much bigger than the larger anti-tank guns or artillery of the period; so what is the big difference?

The difference is the ammunition they fire. Towards the end of WWII the British especially began to experiment with something called sabot rounds, which are projectiles loaded into oversized shells and fired at hyper velocities. Discarding sabot involves a smaller projectile loaded inside the round, the shell of which strips away from the internal package as it leaves the barrel. You can think of it as wrapping up a pencil and shooting it out of a shotgun - the wrapping comes off but all that energy is still behind that pencil pushing it extremely fast.

The 17 pounder in particular was tested with sabot, which proved to be somewhat of a failure due to the fact it would literally just skip off the Panzer V Panther's armour. The early sabot rounds were very small and most importantly short. They later realized that the longer (lengthwise) a sabot round was the less likely it was to deflect off armour (this led to the development of what is known as the long rod penetrator).

Armor

The armour protection of the tank has drastically changed over time. In WWII the convention was to use steel or even rolled homogenous steel (RHA), typically anywhere between 30-100mm thick. Better guns and penetrators forced tank designers to adapt, adding more armour and introducing the concept of sloped armour. Sloped armour will either cause an incoming round to skip off the surface, or force it to penetrate a larger effective armour value than the tank actually has due to trigonometry.

In the 1980s we saw the first uses of what is known as composite armour like CHOBAM, most of which is still secret. It is known, however, that it uses several different layers of material including steel, aluminum, ceramics and possibly even depleted uranium. The sandwiching of these layers makes the effectiveness of the armour much greater than an equal amount of steel RHA. Reactive armour has also been developed, which allows the armour to literally react and defeat both kinetic energy penetrators and chemical-based explosives. The Russian T series in particular has incorporated explosive reactive armour, which can potentially defeat some incoming sabot rounds.

In modern tanks we have seen the effective armour value rise to enormous levels that would have left a WWII tank stuck in the mud. The M1A2 Abrams has effective armour values of over 900mm on the turret and 600 on the hull against kinetic energy penetrations, and over 1200 against HEAT(high explosive anti-tank) rounds. The Russian T-80 has anywhere from 280-800mm of effective armour on the turret, and 750 on the glacis of the hull. Compare this to the Russian T-34 which was put into service in 1941, which had only about 90mm of effective armour.

Penetration

The newer sabot rounds fired by the M1A2 can penetrate over 600mm of armour at 2,000 meters. This is easily capable of slicing through the front armour of the Russian T-72s we saw during Desert Storm. If push came to shove, the U.S. could field its depleted uranium sabots capable of even more penetration. The typical Soviet sabot from its 125mm gun (mounted on the T-72 and T-80) has similar penetration of 600-650mm at 2,000 meters. An interesting note is that the Russians (as per their long standing doctrine) prefer to use cheaper steel sabots because they reduce costs. Oddly enough they also carry more muzzle velocity than typical U.S. sabots and are similar in penetration.

Tiger vs Abrams

Recently I was asked if any WWII gun would be capable of defeating the armour of a MBT, and the answer is no. Even at point blank range to the flank of a modern tank the rounds would not penetrate, even the mighty 88mm L71 mounted on the Tiger II tank. Even spalling damage would not be possible, as the MBTs have built in spall liners for the crew cabin that prevents shrapnel kills from partial penetration. The only possible penetration would be in very small vulnerable areas like the turret ring, and even that would probably only cause partial penetration if at all.

A WWII era tank would never even make it to point blank range with a MBT. Most likely the modern MBT would spot it first through its series of electronic visual aids, and score a first round kill at extremely long range. The computerization of modern tanks is simply astounding; the Leopard II tank in particular has a fully integrated virtual map of the world outside the tank that it uses to coordinate with other members of its platoon and to mark enemy targets. New technology is in prototype stage which will detect the origin of incoming rounds and plot a counterfire solution before the enemy has a chance to reload.

The people that make the best Leopard II tankers are those who were very good at video games when they were children. This is the trend that will continue in the forseeable future as tanks are modernized worldwide. The German Leopard II is widely considered the finest and most modern tank in the world (its gun is also the same as the M1A2 Abrams, and was made by the same company that built the Panzer V Panther's Gun in WWII). The M1A2 is beginning to get a little long in the tooth, and efforts are underway to design a new U.S. MBT.

My own personal conversations with a M1A2 commander led to a funny analogy. While playing a favourite game of mine, I was commanding a Panzer IIc built in the late 1930s. I complained about how the commanders view on the turret spinning around made me slightly dizzy. He remarked to me "Then you will never be a tank commander, because the view is pretty much like a video game". Whatever the next generation of tank, it seems it will be more familiar to the XBox generation rather than that of the Greatest generation.

5 comments:

Maybe the best application of the comparisons is not so much the Abrams and Leopard vs. other opponents but the various older models that might encounter each other. There are still M-60s and T-72s out there in use by smaller nations. How would it be if they went head to head? Or if the T-72 went against the T-72? Then it might come down to targeting technology, ammunition, and, of course, training and tactics.

Well the M48s and M60s were really either just about equal to the Soviet tanks or inferior. The U.S. didn't leap ahead in tank design until the M1 Abrams. The best examples and information would probably come from the Israeli wars, I will look into those.

The most balanced modern matchup would probably be the M1A1 vs the T-80. They're about even, though I'd give the edge to the Abrams because of the greater range of its gun.

I suspect (I have not studied the issue) that tank development since WWII has been based on both mission and the likely opponents. Smaller nations (except Israel) do not do tank development so they take what the market offers. And these procurement actions are not always based on good science, i.e., corruption and politics.

So a question would be what is the likely outcome of both and individual encounter between an M-60 and a T-72, and larger battles. Is the M-60 necessarily second best? How would the M-60 units prevail?

I remember reading about the 1968 war in which Israeli tanks overpowered Egyptian(?) tanks because the Soviet-supplied hardware lacked air conditioning. I'm sure there were other factors, but the crew with the most on the ball has a great advantage.

In the air the Japanese Zero was better than the Wildcat or the Tomahawk. But well-trained crews developed tactics that overcame the deficiencies. Could it be said that Sherman crews were able to overcome their tanks' deficiencies?

That is an interesting comment about the air conditioning. What seemed like a needless luxury in the Soviet Union was an absolute necessity if you are going to be locked in a metal coffin in the desert.

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